Chronic Tic Disorder, including Tourette Syndrome, (CTD) is a relatively common and typically impairing neurodevelopmental disorder of childhood. CTD is associated with deficits in cogntive control, including working memory and response inhibition, and dysfunction of cortico-striatal circuits. Although medications targeting these circuits have been moderately effective in reducing CTD symptoms, Habit Reversal Training (HRT), a behavioral technique, has shown efficacy in providing durable symptom relief without the serious side effects associated with pharmacotherapy. This project aims to clarify the functional anatomy of key circuits subserving cognitive control in youngsters with CTD, to examine hypothesized mechanisms of cognitive enhancement associated with HRT, and to compare these mechanisms to those identified for medication treatment of ADHD. Determining the neural basis of behavioral interventions, such as HRT, and establishing the generalizability of these findings, has the potential to significantly enhance development of improved treatment strategies for CTD, including the development of optimal treatment regimes for individual patients. As such, the aims are highly consistent with the overal goals of the CIDAR. A total of 60 youngsters (aged 7-16) with a DSM-IV Chronic Tic Disorder will receive eight weeks of HRT using a manualized treatment protocol developed and previously tested by our group. Youngsters will also undergo comprehensive clinical, cognitive/EEG, and fMRI evaluation at baseline and post-treatment. A reduced clinical and cognitive/EEG battery will also be collected mid-treatment and three month follow-up (responders only) to examine course and durability of response. All participants will be initially recruited and screened by the Research Assessment Unit (RAU) which will also recruit a matched sample of normal controls to allow for baseline clinical, EEG/fMRI comparison with the CTD and Project III ADHD patient samples. The fMRI and EEG/Cognitive components of the study will be executed through close collaboration with the Imaging and Research Methods (RMC) Cores, respectively. Finally, treatment-related findings from this project will be systematically compared to those from Project III in order to document the potential commonality of neural mechanisms of treatment response across multiple disorders and treatment modalities.